1  /* mpz_sqrtrem(root,rem,x) -- Set ROOT to floor(sqrt(X)) and REM
       2     to the remainder, i.e. X - ROOT**2.
       3  
       4  Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2005, 2011, 2012, 2015 Free
       5  Software Foundation, Inc.
       6  
       7  This file is part of the GNU MP Library.
       8  
       9  The GNU MP Library is free software; you can redistribute it and/or modify
      10  it under the terms of either:
      11  
      12    * the GNU Lesser General Public License as published by the Free
      13      Software Foundation; either version 3 of the License, or (at your
      14      option) any later version.
      15  
      16  or
      17  
      18    * the GNU General Public License as published by the Free Software
      19      Foundation; either version 2 of the License, or (at your option) any
      20      later version.
      21  
      22  or both in parallel, as here.
      23  
      24  The GNU MP Library is distributed in the hope that it will be useful, but
      25  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
      26  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
      27  for more details.
      28  
      29  You should have received copies of the GNU General Public License and the
      30  GNU Lesser General Public License along with the GNU MP Library.  If not,
      31  see https://www.gnu.org/licenses/.  */
      32  
      33  #include "gmp-impl.h"
      34  
      35  void
      36  mpz_sqrtrem (mpz_ptr root, mpz_ptr rem, mpz_srcptr op)
      37  {
      38    mp_size_t op_size, root_size, rem_size;
      39    mp_ptr root_ptr, op_ptr, rem_ptr;
      40  
      41    op_size = SIZ (op);
      42    if (UNLIKELY (op_size <= 0))
      43      {
      44        if (UNLIKELY (op_size < 0))
      45  	SQRT_OF_NEGATIVE;
      46        SIZ(root) = 0;
      47        SIZ(rem) = 0;
      48        return;
      49      }
      50  
      51    /* No-op if rem == op */
      52    rem_ptr = MPZ_NEWALLOC (rem, op_size);
      53  
      54    /* The size of the root is accurate after this simple calculation.  */
      55    root_size = (op_size + 1) / 2;
      56    SIZ (root) = root_size;
      57  
      58    op_ptr = PTR (op);
      59  
      60    if (root == op)
      61      {
      62        /* Allocate temp space for the root, which we then copy to the
      63  	 shared OP/ROOT variable.  */
      64        TMP_DECL;
      65        TMP_MARK;
      66  
      67        root_ptr = TMP_ALLOC_LIMBS (root_size);
      68        rem_size = mpn_sqrtrem (root_ptr, rem_ptr, op_ptr, op_size);
      69  
      70        if (rem != root)	/* Don't overwrite remainder */
      71  	MPN_COPY (op_ptr, root_ptr, root_size);
      72  
      73        TMP_FREE;
      74      }
      75    else
      76      {
      77        root_ptr = MPZ_NEWALLOC (root, root_size);
      78  
      79        rem_size = mpn_sqrtrem (root_ptr, rem_ptr, op_ptr, op_size);
      80      }
      81  
      82    /* Write remainder size last, to make this function give only the square root
      83       remainder, when passed ROOT == REM.  */
      84    SIZ (rem) = rem_size;
      85  }